1. Field of the Invention
The present invention relates to a device used to tension a drive chain of a bicycle during gear changing.
2. Discussion of the Background
Many bicycles include a transmission device that allows the bicycle to change between multiple gears. Such transmission devices can include a rear derailleur device that includes both a gear changing device and a tension device that are incorporated together as a unit. The gear changing device is used to shift from one gear to another gear by guiding the drive chain of the bicycle to engage with one sprocket of a set of plural sprockets that each provide a different mechanical advantage between an input from a rider to pedals of the bicycle and an output to a rear wheel of the bicycle. The sprockets provide a different mechanical advantage based on a different diameter size of each sprocket. However, as the gears are shifted by changing engagement of the drive chain from one sprocket to another sprocket, the drive chain will naturally slacken, which could allow the chain to disengage from the sprocket, or tighten, which could cause the chain to break, due to the diameter difference from one sprocket to another. Thus, the tension device is provided to account for this phenomenon and maintain the tension of the drive chain as the gears of bicycle are shifted.
The inventors of the present invention have determined that numerous improvements can be made to known designs of bicycle derailleurs.